Contact lenses are a popular means of correcting eyesight and/or changing the color or appearance of eyes. As the technology of contact lenses has evolved, soft contact lenses have been made available by the eye correction industry. Soft contact lenses can be worn for a threshold amount of time per day (a wear threshold). The wear threshold can vary from one contact lens to another, but once the wear threshold expires, it is intended that a user will remove the contact lenses from their eyes.
Some soft contact lenses are reusable for a period of time. For example, soft contact lenses can be reused ten (10) times, thirty (30) times, or the like (a use threshold). In order to ensure cleanliness over an extended period of days, reusable contact lenses are often cleansed between uses. For example, upon expiration of a wear threshold, a user is expected to remove the contact lenses and perform a cleansing routine to cleanse the lenses. Thereafter, the user is expected to store the contact lenses in a sterile, moist environment during a time period the user should not wear contact lenses to avoid fatigue (a resting threshold). Once the resting threshold expires, a user has the option of reusing that contact lens by reinserting the lens into the user's eye. Accordingly, the same contact lens can be used, cleansed, stored, and reused until its use threshold expires. Once the use threshold expires, the user is expected to dispose of the contact lens and begin using a new lens.
In theory, reusable lenses are cost effective, convenient, clean, and pose few risks to the user's eyes. That said, hygiene is one of the most important factors in preventing infections and other problems that affect the short term health of eyes as well as long-term vision. In practice, it has been discovered that users often refuse or forget to follow their prescribed cleansing and sanitary storing routines. This can result from the fact that a manual cleansing process is arduous.
According to a manual cleansing process, a user is instructed to wash his or her hands prior to touching the contact lens or anything that will touch the contact lens. Then, the user removes a contact lens from his or her eye and places it in the palm of his or her clean hand. The user sprays fresh, unused contact lens cleansing solution over the contact lens and allows the solution to pool in the palm of his or her hand. The user rubs the front and back of the lens with a clean finger on their other hand. The user avoids touching the lens with their fingernails because they can carry bacteria and can cut or damage the lens. After having rubbed the lens' surface, the user rinses the lens with fresh, unused cleansing solution.
Once the lens is cleansed, the user places the lens in a clean contact lens storage case, which itself should be cleansed and dried before removing the contact lens from the eye. The contact lens storage case is cleansed by spraying the contact lens storage case with fresh, unused contact solution. Water should not be used to cleans a contact lens storage case because water is filled with bacteria, impurities, and microorganisms. After the contact lens storage case is properly cleansed, the contact lens storage case should be overturned and allowed to air dry. Contact lens storage cases should be stored at a distance from toilets to avoid contamination.
The user places the lens into the clean contact lens storage case and fills the contact lens storage case with fresh, unused contact solution. The user should use at least a threshold amount of fresh, unused contact solution, which can be indicated by a line on the contact lens storage case. The contact lens storage case should not be filled with used solution because used solution can lead to contamination. Once the contact lens storage case is filled with the threshold amount of fresh, unused contact solution, the contact lens remains submerged in the contact solution for a threshold cleansing time. The lens should not be removed before the threshold cleansing time expires to ensure any air bubbles clinging to the lens surface dissipate. This allows the solution to saturate the entire lens surface. Further, the threshold cleansing time allows the contact solution to fully dissolve proteins and lipids, which can build on the lens surface.
A user's lack of compliance with the foregoing regimen leads to major complications. Users often deposit proteins and lipids on the surface of a contact lens. Further, pollution and dirt deposit on the surface of a contact lens. As these deposits build up, users experience decreased vision, irritation, and conjunctivitis. Depending on the severity of conjunctivitis, a user can experience redness, itchiness, pain, and photophobia. The industry has attempted to reduce the complications associated with reusable soft contact lenses, but currently available solutions are ineffective or rejected by users.
One proposed solution involves reducing the use threshold. The idea is as follows: if users will not properly cleanse and store their contact lenses, then reducing the use threshold will cause the lenses to be disposed of before protein, lipids, pollution, and/or dirt deposits build to dangerous proportions. So the industry created soft contact lenses having reduced use thresholds as low as a single use. This solution seems plausible but has been ineffective in practice. That is, merely reducing the use threshold is prohibitively expensive. As of now, single use contact lenses cost significantly more than contact lenses having a longer use threshold. In some circumstances, users wear single-use lenses multiple times in order to save money, and such unintended use leads to protein and lipid build up, contamination, and eye infection.
Another proposed solution involves using an ultra-sonic machine to clean lenses using ultra-sonic vibrations. When the user is ready to remove their contact lenses, the user opens the lid of the ultra-sonic machine, removes his or her contact lenses, places the contact lenses in a basket inside the ultra-sonic machine, fills the ultra-sonic machine with a threshold amount of fresh, unused contact solution, closes the lid, and presses a button to initiate ultra-sonic vibrations. When initiated, ultra-sonic frequencies cause air bubbles to develop and move about the contact lenses. Manufactures of ultra-sonic machines assert that the generated air bubbles cleans the lenses in as little as two minutes and alleviate the user's previous need to rub the lenses with their fingers and store the lenses in solution for the threshold cleansing time. As such, according to manufactures of the ultra-sonic machines, the contact lenses are cleansed just as effectively with less time and less effort.
However, in practice, the industry has discovered the ultra-sonic machines leave much to be desired when it comes to cleansing contact lenses. While ultra-sonic vibrations cause air bubbles to move through the solution, they do not move in any particular direction. As such, it is only a matter of chance if air bubbles affixed to the lens surface dissipate prior during vibration. Air bubbles that fail to dissipate from lens surfaces prevent the lens from being properly cleansed and can lead to infection. As such, doctors recommend rubbing contact lenses prior to using the ultra-sonic machine, regardless of the manufacturer's instructions. In practice, users tend to follow procedures that are less time consuming, so they forget or choose to forgo the rubbing process, and ultra-sonic machines provide a false sense of security regarding contact cleanliness.
Further, contact lens cleansing solution has a recommended storage threshold, as explained above. To effectively ensure all air bubbles dissipate from the lens surface and all proteins and lipids are dissolved, it is recommended that contact lenses remain submerged in cleansing solution for a threshold cleansing time. The manufacturers of ultra-sonic machines tout that ultra-sonic technology cleanses lenses in about two minutes, after which the lenses can be removed from the machine. Such an instruction provides a false since of lens cleanliness because two minutes is insufficient for the cleansing solution to dissolve proteins and lipids. Thus, if the user removes the lenses from the ultra-sonic machine and inserts them into their eyes after two minutes of cleansing, at least two problems occur: (1) the user risks wearing lenses that are not sufficiently cleansed, and (2) the user's eyes can be susceptible to hypoxia (i.e., oxygen loss to the eye).
Therefore, to properly clean contact lenses while using an ultra-sonic machine, a user would remove the lenses from the ultra-sonic basket and store them in a storage case that is filled with fresh, unused solution. As can be seen, in order to properly clean lenses using an ultra-sonic machine, a user would first rub the lenses with their fingers, place the lenses in the ultra-sonic machine for two minutes, remove the lenses and store them in a storage container for the threshold cleansing time (and/or resting threshold time). Therefore, in use, the ultra-sonic machine adds steps to the contact lens cleansing process and provides a false sense of cleanliness that leads to an increased risk of eye infection.
Further, ultra-sonic machines must be cleansed. As with other lens cleansing devices, contact solution, rather than water, should be used to rinse the machines. In addition, to deep clean an ultra-sonic machine, a user unplugs the machine and allows it to rest for at least one hour. Then, the machine is wiped throughout with a sponge or cloth dampened with detergent and hot water. Thereafter, the machine is thoroughly rinsed to remove all soap residue. Being that water includes contaminates, rinsing with contact solution is recommended. It has been determined that users rarely, if ever, perform this cleansing regimen. Further, users often damage a machine's electronics during the cleansing process.